The present invention relates to high impact wear resistant tools that may be used in machinery such as crushers, picks, grinding mills, roller cone bits, rotary fixed cutter bits, earth boring bits, percussion bits or impact bits, and drag bits. More particularly, the invention relates to inserts having a carbide substrate with a non-planar interface, and an abrasion resistant layer of superhard material affixed thereto using a high pressure high temperature press apparatus. Such inserts typically shave a superhard material layer or layers formed under high temperature and pressure conditions. The high temperature and pressure conditions typically occur in a press apparatus designed to create such conditions. The superhard material layer or layers may be cemented to a carbide substrate. The carbide substrate may contain a metal binder or catalyst such as cobalt. The carbide substrate is often softer than the superhard material bonded to the carbide substrate. Some examples of superhard materials that high-temperature, high-pressure (HTHP) presses may produce and sinter include cemented ceramics, diamond, polycrystalline diamond (PCD), and cubic boron nitride.
An insert is normally fabricated by placing a cemented carbide substrate into a container or cartridge with a layer of diamond crystals or grains loaded into the cartridge adjacent a face of the substrate. A number of such cartridges are typically loaded into a reaction cell and placed in the HTHP press apparatus. The cemented carbide substrates and adjacent diamond crystals are then compressed under HTHP conditions, which promotes a sintering of the diamond grains to form a PCD structure. As a result, the diamond grains become mutually bonded to form a superhard material layer over the substrate interface and the resulting superhard layer is also bonded to the substrate interface.
Such inserts are often subjected to intense forces, torques, vibration, high temperatures and temperature differentials during operation. As a result, stresses within the structure may begin to form. Drill bits, for example, may exhibit stresses aggravated by drilling anomalies during well boring operations, such as bit whirl or bounce often resulting in spalling, delamination, or fracture of the superhard material or the substrate thereby reducing or eliminating the insert's efficacy and decreasing overall drill bit wear life. The superhard material of an insert sometimes delaminates from the carbide substrate after the sintering process as well as during percussive and abrasive use. Damage typically found in percussive and drag bits may be a result of shear failures, although non-shear modes of failure are not uncommon. The interface between the superhard material and substrate is particularly susceptible to non-shear failure modes due to inherent residual stresses.
U.S. Pat. No. 7,258,741 to Linares, et al., which is herein incorporated by reference for all that it contains, discloses synthetic monocrystalline diamond compositions having one or more monocrystalline diamond layers formed by chemical vapor deposition, the layers including one or more layers having an increased concentration of one or more impurities (such as boron and/or isotopes of carbon), as compared to other layers or comparable layers without such impurities. Such compositions provide an improved combination of properties, including color, strength, velocity of sound, electrical conductivity, and control of defects. A related method for preparing such a composition is also described, as well as a system for use in performing such a method, and articles incorporating such a composition.
U.S. Pat. No. 6,562,462 to Griffin, et al., which is herein incorporated by reference for all that it contains, discloses a PCD or a diamond-like element with greatly improved wear resistance without loss of impact strength. These elements are formed with a binder-catalyzing material in a HTHP process. The PCD element has a body with a plurality of bonded diamond or diamond-like crystals forming a continuous diamond matrix that has a diamond volume density greater than 85%. Interstices among the diamond crystals form a continuous interstitial matrix containing a catalyzing material. The diamond matrix table is formed and integrally bonded with a metallic substrate containing the catalyzing material during the HTHP process. The diamond matrix body has a working surface, where a portion of the interstitial matrix in the body adjacent to the working surface is substantially free of the catalyzing material, and the remaining interstitial matrix contains the catalyzing material. Typically, less than about 70% of the body of the diamond matrix table is free of the catalyzing material.